The top wall of high-temperature kilns is customarily designed as an arched vault made of refractory bricks. However, this design generates considerable lateral thrust forces which must be supported by the side walls or by a rigid external casing, and it brings about a waste of internal space, since the inner volume of the arch is of hardly any use and moreover gives rise to an uneven distribution of heat and to a stagnation of hot gases within the kiln.
It has been suggested, as a remedy to these drawbacks, to design the top wall of a kiln as a flat hanging ceiling, the bricks in this ceiling being pre-assembled in pairs over metal hooks or lugs hanging from a rigid structure erected above the ceiling at the time of final assembling. However, this design makes it difficult to ensure a proper gas-tightness of the top wall. On another hand, the metal components embedded in the brickwork must endure high temperatures, so that the strength of the ceiling is not too satisfactory. This drawback becomes even worse when a substantial heat-insulating layer is provided on top of the ceiling, since it will increase the effect of the temperature on the suspension pieces which are not cooled. Finally, these suspension components render the installation of the insulating material more difficult and costly.
Alternatively, it has also been suggested to provide the ceiling bricks with horizontal channels and to slip into these perforated bricks horizontal bars supported at intervals by metal hooks hanging from a rigid overhead structure. This design presents the same drawbacks as the first-mentioned one and is even more complicated and costly to assemble.
The purpose of this invention is to provide a design of the top wall in a high-temperature kiln which will eliminate the above-mentioned drawbacks.